Dipper



March 8, 1932. MORIN 1,848,643

DIPPER TRIP MECHANISM FOR EXCAVATING MACHINES Filed Dec. 13. 1929 3 sheets-sheet 1 llllllllll h I N O o o Q INVENTOR.

ATTORNEYS.

March 8, 1932. G, MORIN 1,848,643

DIPPER TRIP MECHANISM FOR EXCAVATING MACHINES Filed Dec. 13. 1929 3 Sheets-Sheet 2 NVENTOR.

Z1 TTORNEYS.

G. G. MORIN March 8, 1932.

FOR EXCAVATING MACHINES DIPPER TRIP MECHANISM Filed Dec. 15, 1929 3 Sheets-Sheet 3 Q Q k INVENTOR. r

TTORNEYS.

' to a minimum.

Patented Mar. 8, 1932 warren STATES GEORGE G. MORIN, OF HOLYOKE, MASSACHUSETTS DIPPER TRIP MECHANISM FOR EXGAVATING MACHINES Application filed December 13, 1929. Serial No. 413,890,

This invention relates to mechanism for tripping the latch which holds the bottom of the bucket or dipper in an excavating machine. Various forms of this type of mechanism have been proposed. In excavating machines, the dipper is moved back and forth in order to load the dipper and to discharge thesame inthe desired position. This motion of the dipper of course varies the distance between it and the cab which houses the main operating mechanism of the machine. In order to insure that the cable which is connected to the dipper latch mechanism is at all times in condition to operate the latch, it is customary to employ some form of slack take up device operating on the cable and constantly paying out or taking in cable according to the position of the dipper.

This invention relates to the improvement of mechanism of thisgeneral character and has several specific objects. One object is to avoid the necessity of the constant applica tion of power to the dipper trip operating mechanism in order to keep the slack in the cable taken up. Another object is to eliminate the use of friction driving mechanism. Another object is to provide a power operated trip mechanism in which the normal trip operating mechanism can be supplemented or replaced by the power of the dip per operating mechanism. Another object is to provide a spring take up mechanism in which danger of spring breakage is reduced Other objects will appear from the following description and claims.

Referring to the drawings: Fig. 1 is a diagrammatic side elevation of an excavating machine illustrating the gen-- eral environment of my invention;

Fig. 2 is a bottom plan view of the dipper;

Fig. 3 is a detail of mechanism showing a modification;

Fig. 4: is an elevation of the dipper trip mechanism looking from the left in Fig. 1;

Fig. 5 is an elevation of the mechanism shown in Fig. 4 taken in median section sub-- stantially on line 55 of Fig. 4;.

Fig. 6 is an elevation of the mechanism shown in Fig. 4% looking from the opposite direction from Fig. 5;

Fig. 7 is a detail of a brake operating piston; and

Fig. 8 is a. diagrammatic view of the piping arrangement.

Referring first to the general view of the excavating machine shown in Fig. 1, the operating mechanism is supported by a frame or truck body 10 which supports a cab 11 housing the boiler or other motive power and the various engines for operating the different movements of the dipper. A boom 12 is pivoted at 13 to the frame 10 and is raised and lowered by any suitable mechanism which it is not necessary to illustrate here. A dipper handle 14 supporting the dipper 15 at its end is mounted upon the boom, being operated by the usual crowding and hoisting engines. The bottom 16 of the dipper is provided with a hinge 17 and with a latch bar 18 engageable with a latch plate 19 on the dipper. Pivoted at 20 to the latch bar is a lever 21 swinging at 22 upon the bottom of the dipper and having secured to its end a tripping chain 28. This chain is wound about a small drum 24 rotatable upon the dipper handle and having secured to it a lever 25. A trip cable 26 is secured to this lever and passes around guide sheaves 27 and 28 to a tripping mechanism, preferably contained withinthe cab 11 and described in detail below. A spring 29 holds the lever in a position permitting latching of the bar 18. This latching mechanism may be of any standard or desired type and does not in its details form a part of my present invention.

The cable 26 is operated upon by two different mechanisms, one serving to keep it constantly taut and the other operable when the bucket is to be tripped to exert a sudden pull upon the cable and to withdraw the latch bar 18 from the latch plate 19. The slack take-up mechanism will be described first. The cable 26 is wound upon and is secured to a drum 30 having flanges 31 to prevent the cable slipping off. Preferably one of these flanges is formed as a brake drum 32 for a purpose to be described. This drum is loose upon the shaft 33, which is freely rotatable upon a frame 34 carried by thetruck body 10. A spiral spring 35, of considerable length, is placed interiorly of the drum, one end of the spring being anchored at 36 to the drum and the other end anchored at 37 to the shaft. In order to hold the shaft stationary in one direction, a ratchet 38 6) is secured to it-in any suitable manner so as to be engaged by a pawl 39 pivoted at 40 to the frame 34. The shaft may be rotated manually to exert any desired initial tension upon the spring and this adjustment will be maintained by the action of the'ratchet and pawl described. V The mechanism including the drum and spring serves to exert a steady pull upon the cable sutficient to maintain the cable taut at all positions of the dipper. When the trip mechanism is to be operated, the drum is initially held against rotation so that the cable is temporarily firmly anchored to the frame of the machine. For this purpose, a brake band 41encircles the brake drum 32, being anchored at 42 to the frame and at 43 to a link 44. This link has pivotal connection with an operating lever 45 pivoted at-46 to the frame and adapted to be swung upon its pivot by a push bar 47; In order to provide an adjustment between the push bar and the lever, they are pivoted together by apin which can be placed selectively in anyone of a plurality of holes 48 in the lever. The push bar is operated by a piston 49- (Fig. 7) run ning in a cylinder'50, the operation'of which 7 can be considered better after a description of some additional mechanism.

With the drum held. stationary'by the brake, the cable is pulled at a point between P the drum and the dipper in order to trip the latch mechanism. In the present case, the preferred form of mechanism is a movable sheave 51, rotatable ina carrier 52 supported upon the shouldered end of a piston rod 53. This rod is guided in one head 54 of a pneumatic cylinder 55. At the other end, the piston rod is reduced at 56 to receive a piston 57 fitting snugly within the cylinder. A spring 58 is mounted between the piston and the head 54 so that the piston is always caused to return to the position shown in Fig. 5 after the pneumatic pressure has been relieved. A cylinder head 59 closes the second end of the cylinder and supports the small cylinder previously described.

It is preferable, in order to-avoid undue shock during the operation of the mechanism, to employ a spring shock absorber acting to cushion the end of the stroke of the piston in each direction. Behind the piston 57 is located a second spring 60 abutting a collar 61 which fits against a shoulder 62 on the piston rod. As the piston is pushed to the left in Fig. 5, the collar 61 will strike the cylinder head 54 and will gradually bring the piston to rest. To cushion the stroke in the opposite direction, a spring 63 is mounted between the carrier 52 and a collar 64 held in place by a shouldered portion 65 of the piston rod. In Fig. 5 this collar is shown as making contact with the outside of the cylinder head 54 and therefore permitting the spring 63 to bring the piston slowly to rest.

It will readily be seen that if the piston is moved to the left in Fig. 5, the sheave 51 will be carried in a direction to exert a pull on the cable 26. I The operation of the piston is under the control of the operator by means of the mechanism now to be described. Reference will first be made to Fig. 8 which shows in diagrammatic form an arrangement of piping and valve mechanism suitable for the purpose. A main supply pipe 7 0 for steam or air under pressure fitsinto a valve casing 71 bored out internally to receive a valve piston 72. This type of valve is preferred for the present purpose and is described and claimed in my oopending appiication for patent, Serial No. 244,463, filed an. 4, 1928; but other forms of valve might be employed if desired. In the preferred form, the piston has a central annular channel 73which in the position of Fig. 8 joins a port 75 leading to pipe 76 with a port 77 leading to an exhaust pipe'78. The piston 72 has secured to it a rod 79, and also a spring 80 which normally holds it in the position of Fig. 8 andis apertured from end to end so that the pressure fluid exerts a balanced action on it. A cable 81 is secured tothe end of the piston rod 79 and, as shown in 4, passes around a sheave 82 to a fixture'83 mounted upon a controllever 84 pivoted at 85 to and forming art of one of the main dipper control levers .86. If this handle is moved into and out of the plane of the paper in Fig. 4, it will produce no efiect upon the valve just described. When the. valve is to be operated, the upper I portion 84 of the handle is rocked upon its pivot 85, causing the rod 79 to be shifted and the piston 7 2 to be displaced to the left in Fig.

8. In this position, the fluid under pressure from pipe 7 0 passes directlyinto the port 7 5, the displacement of the piston being sufficient to carry it, just beyond this port.

When the valve is in the operating position, the fluid under pressure passes'through pipe 7 6 to a port 87 in the bottom of the cylinder 50. In the normalposition of the piston 49. it partly closes a port 88 which is connected" by a passage 89 with the interior of the cylinder 55. As the fluid, pressure reaches the port 87, it first causes the piston 49 to be raised, due to the partial closure of. port 88. operating the drum brake as described; and

' then, as the piston uncovers the port 88, the

fiuid pressure will have free entrance into the main operating cylinder 55 and will cause displacement of the piston 57 in a direction to exert tension upon the trip cable. When the handle 84 is restored to its normal position,

iii)

themain control valve will again assume the position of Fig. 8 in which the port 75 is connected, through the annular passage 73, with an exhaust pipe 78. This first vents the cylinder 55, permitting the piston to return to its inactive position; and then, as the fluid pressure drops, the piston 49 will again be lowered, releasing the brake mechanism. It will be seen that the piston 49 is operated before the piston 57 during the tripping o oration, and is released after the piston 54 at the termination of the tripping operation. This insures that the end of the cable will always be anchored by the brake mechanism when tripping tension is being applied.

It is preferable to employ a simple mechanism preventing the accumulation of undue amounts of condensation within the cylinder 55. In the form shown, a pipe 90 runs from the lowermost part of this cylinder and terminates in a valve 91. Within this valve is a valve seat and a cooperating poppet valve 92 normally held open (as shown in Fig. 8) by a spring 93. This permits the lower degrees of fluid pressure within the cylinder to blow out any water of condensation; but as the pressure builds up, the valve 92 will be forced closed and leakage of steam during the operation of the piston prevented.

The operation of the trip mechanism described should be clear from the description above and need not be gone over in much detail. As the dipper is moved in and out by its usual operating mechanism, the drum will rotate, the spring exerting only enough tension upon it to keep the cable taut. When it is desired to trip the dipper bottom, the handle 8% is rocked, first causing the brake band 41 to be contracted upon the brake drum by the operation of the piston 49 and then causing displacement of the sheave 51 to exert a tripping tension upon the cable. If from any cause the resistance of the latch mechanism is so great that the pneumatic mechanism described does not have sufficient power to trip it, the crowding mechanism for the dipper may be brought into play moving the dipper away from the cab and therefore exerting a tension upon the cable which is anchored by the drum and brake mechanism. In simple installations the pneumatic operating mechanism may be eliminated and the foot power brake operating device shown in Fig. 3 substituted. In this case, the parts which are not changed are indicated by primed numerals. The rocking brake operating lever is provided with a pin running in a slot 96 formed in the end of a treadle member 97 pivoted to a standard 98 on the frame. lVith this simplified form of the device, the drum normally operated by the spring, as described, to take up the slack in the cable may be held stationary by de pressing the treadle 97. The bucket may then be pushed away from the cab by the crowding spring breaking upon breakage of the cable 26 is eliminated. If the cable should break,

the spring would of course cause the drum to revolve rapidly and were the shaft fixed in the frame the inertia of the heavy drum would cause it to overtravel when the spring was completely unwound. unwind the spring past its normal position would almost inevitably result in breakage. In the structure described, however, this cannot occur since overtravel of the drum would not be met by a resistance of a fixed shaft, but on the contrary would merely cause clicking of the pawl 39 over the ratchet until the momentum of the parts had dissipated itself.

What I claim is:

1. A dipper tripping mechanism'of the type in which latch mechanism on the dipper of an excavating machine is controlled by a cable extending to the boom-supporting frame of the machine and hence having a path varying in length according to the position of the dipper, comprising a drum located at the frame end of the cable and having the cable wound upon it, a spring acting on the drum to rotate it in a direction to wind the cable further thereon and hence to take up slack in the cable, a brake for arresting the rotation of the drum and hence anchoring the cable, and power actuated mechanism operable on the cable between the drum and the dipper independently of the motion of the dipper for exerting tension on the anchored cable and hence tripping the latch.

2. A dipper tripping mechanism of the type in which latch mechanism on the dipper of an excavating machine is controlled by a cable extending to the boom-supporting frame of the machine and hence having a path varying in length according to the position of the dipper, comprising a drum located at the frame end of the cable and having the cable wound upon it, a spring acting on the drum to rotate it in a direction to wind the cable further thereon and hence to take up slack in the cable, a brake for arresting the rotation of the drum and hence anchoring the cable, a pulley over which the cable passes between the drum and the dipper, power actuated mechanism operable independently of the motion of the dipper to shift the pulley bodily and thus to exert tension on the anchored cable and to trip the latch, and a single control for said brake and said mechanism.

3. A dipper tripping mechanism of the type in which latch mechanism on the dipper of an excavating machine is actuated by a cable, comprising a drum, a spiral spring acting on the drum to cause slack in the cable to be taken up, a brake for locking the drum The attempt to a pulley around which the against rotation,

the drum and the latch cable passes between mechanism, and'mechanism operating successively to set the brake and then to shift the pulley to tension the cable.

4. A dipper tripping mechanism of the type in which latch mechanism on the dipper of an excavating machine is actuated by a cableycompri'sin'g a drum, a spiral spring acting on the drum to cause slack in the cable to be taken up,a brake for locking the drum against rotation, a pulley around which the cable passes between the drum and the latch mechanism, and a pair of pneumatic cylinders and associated'pistons acting respectively to set the brake and to move the pulley bodily, the fluid inlet to the second cylinder being controlled by a port in the side of the first, whereby the pulley will be moved only after the brake is set.

5. A cable tensioning mechanism for preserving in taut condition the cable of dipper tripping mechanism or the like, comprising a frame, a shaft rotatably mountedin the frame, a drum mounted on the shaft and rotatable relatively thereto, a spiral spring having one end connected to the shaft and the other to the drum, and a ratchet and pawl mechanism connecting the frame and the shaft in a direction so that they are locked together under the tension exerted by normal ceiling of the spring but the shaft is free to rotate in the frame in the reverse direction] 6. A dipper tripping mechanism of the type in which latch mechanism on the dipper of an excavating machine is actuated by a cable, comprising a frame, a shaft rotatably mounted on the frame, a drum rotatably mounted on the shaft} a spiral spring havingone end connected to the shaft and the other to the drum, a brake mechanism operative to hold the drum stationary with respect tothe frame, a ratchet and pawl mechanism adjustably connecting the frame and the shaft, andmechanism operative on the cable between the drum and the latch for exerting a tripping tension uponflthe cable when the drum is held stationary.

7. A dipper tripping ,mechanism of the exert tension on the anchored cable and to trip the latch, and control mechanism adapted for initial actuation by the operator and operating automatically thereafter first to cause setting of the brake and then to cause actuation of the pulley shifting mechanism.

7 In testimony whereof I have affixed my signature. 7

GEORGE G. MORIN.

type in which latch mechanism on the dipper of an excavating machine is controlled by a cable extending to the boom supporting frame of the machine and hence having a path varying in length according to the position ofvthe dipper, comprising a drum located at the frame end of the cable and having the cable wound upon it, a spring acting on the drum to rotate itin a direction to wind the cable further thereon and hence to take up slack in the cable, a brake for arresting the rotation of the drum and hence anchoring the cable, a pulley over which the cable basses between the drum and the dipper, mechanism operable independently of the motion of the dipper to shift the pulley bodily and thus to 

